It is known for gas turbine compressor and turbine blades to be securely retained axially in their respective discs. A typical method of providing blade axial retention is by the use of lock plates 10 and ‘pre-bents’ 12 as shown in FIG. 1.
In such arrangements, the assembly method begins with the blades 20 being located sequentially within the disc 30. Some blades are then advanced forward in the disc to provide space for a number of lock plates 10 to be rotated into place between the blade rim and the disc 30. The blades 20 are then positioned and lock plates 10 evenly distributed around the disc 30. The remaining spaces are filled with ‘pre-bents’ 12 which are then hammered flat to secure them in place.
During disassembly of the bladed disc the ‘pre-bents’ 12 are removed by accessing the front of the assembled disc 30 and passing tooling between the blades 20 to buckle the ‘pre-bents’ 12 rearwards. These buckled ‘pre-bents’ 12 are then removed allowing space to spiral some of the blades down and thereby reverse the assembly procedure
A significant problem with this technique is that access is required to the front of the disc 20 in order to be able to buckle the ‘pre-bents’ 12 rearwards and remove them from the disc 20. In a multi-stage turbine system this will not be possible and therefore alternative methods of disassembly, such as cutting the lock plates 10, must be used. Such alternative methods carry a significant risk of damaging the high value disc 30 and blades 20.